An operator of a system often relies upon visual indicators to show, among other things, the status of the system. For example, the operator of an aircraft can be provided with indicators such as a visual indicator of the horizon line of the aircraft, a visual indicator of the airspeed of the aircraft, and a visual indicator of the altitude of the aircraft. At one time these visual indicators were provided using analog, mechanical displays. Increasingly, electronic display panels, comprised of a number of individually addressable pixels, are being used to provide visual indicators of system status. Typically, to display the symbology that provides visual indicators, a graphics processing unit is used to generate the symbology, which is then displayed on a display. The proper generation of the symbology is needed to provide the operator an accurate indicator of system status.
Because of the importance of correctly displaying critical symbology, the data sent to the display is typically monitored to determine if the critical symbology was correctly rendered. In a typical prior art system, the display system includes a server that receives information regarding the images to be displayed from a display processor, such as an airborne system, and generates commands to produce images. The commands are received by a graphics processing unit, which uses the commands to generate the image to be displayed by determining the state of each pixel in the image based on the generated commands. The display receives the information regarding each pixel in the display and sets each pixel that comprises the image to the proper state.
In prior art systems, the data produced by the display processor and the data produced by a rendering engine can be monitored or checked. The display commands produced by the display processor from input data are received by a comparator circuit (or processor). The comparator circuit also receives the same input that the display processor uses to generate the display commands. Since in prior art systems the input data from the display commands can be extracted, the comparator circuit compares the data from the display processor with data that the comparator circuit calculated from the input. If there is a match, this part of the verification passes and the display processor is considered to be producing the correct commands from a given input.
In one prior art system, the display processor also inserts a sequence of test commands in the commands sent to the rendering engine. These commands generate test images in an extended area of the display that is not visible to the user. The display output of the rendering engine sent to the extended area of the display is sampled and a cyclic redundancy check (CRC) value is calculated from the sample data. The CRC value is then compared to an expected CRC value to determine if there is a failure in the rendering engine.
While the prior art systems were adequate for monitoring many display systems, an increasing reliance on commercial off the shelf (COTS) display chips has made the task of monitoring display systems more difficult and problematic. One reason is because the architecture of display systems, especially those based on COTS display chips, has undergone changes that render previous monitoring systems inadequate. For example, some COTS rendering engines include integrated circuits that may incorporate functions previously performed in the display processor. This change makes previous methods of monitoring display systems unusable, as it is impractical to extract the commands used to generate pixel data.
Accordingly, it is desired to provide a method and system for image monitoring. Furthermore, the desirable features and characteristics of the present invention will be apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.